Univariate linear regression analysis showed that age (P = 0.023), male gender (P < 0.001), Chinese ethnicity (P < 0.001), smoking habits (P = 0.001), diabetes mellitus (P = 0.004), haemoglobin (P < 0.001), serum triglyceride (P = 0.041), serum LDL Cholesterol (P = 0.018), and serum PTH (P = 0.045) levels were predictors of serum 25(OH)D levels. This evidence concerns the gene PTH and diabetes mellitus.